Development and Evaluation of a Low-Cost Solar Dryer for Pepper in Plateau State

Post-harvest losses in pepper production in Plateau State, North Central Nigeria, are estimated to exceed 30 percent, largely attributable to inadequate drying infrastructure among smallholder farmers. This study designs, constructs, and evaluates a low-cost indirect solar dryer fabricated from locally sourced materials including angle iron, corrugated galvanised roofing sheets, glass panes, and a black-painted absorber plate. The dryer was evaluated for thermal performance and drying efficiency using Tatase pepper (Capsicum annuum) as the test crop during the dry season in Jos. Parameters monitored included ambient temperature, collector outlet temperature, relative humidity, and mass loss of pepper over a six-day drying period. The moisture reduction from 78 to 11 percent wet basis was achieved in 36 hours of effective solar drying, compared to 72 hours for open sun drying under the same ambient conditions. The solar dryer maintained an average collector temperature of 62 degrees Celsius against an average ambient temperature of 29 degrees Celsius. The dried pepper retained superior colour and lower aflatoxin contamination compared to open sun-dried samples. Economic analysis showed a payback period of 14 months for a dryer unit serving 10 farmers in cooperative arrangement. The study draws on recent solar drying literature for tropical agricultural commodities. Recommendations are provided for the Plateau State Agricultural Development Programme and rural energy technology extension services. Keywords: solar dryer, pepper, post-harvest loss, thermal performance, Plateau State